1. Field of the Invention
The present invention relates to a strip storage arrangement including a strip storage unit for strips, particularly metal strips, which travel continuously in the form of loops in strip treatment units. The strip storage unit includes a strip drive at the entry side, a strip drive at the exit side and at least one tension drive for generating the necessary tension in the loop strands of the strip.
2. Description of the Related Art
In processing plants for e.g. metal strip of steel, aluminum or the like, or for plastic tapes or paper bands and also for foils, wire and the like with continuous operation in the processing unit, it is necessary to provide a strip storage unit each at the entry side and at the exit side for bridging the periods of stoppage when coils or reels are being exchanged. In treatment arrangements of metal strip, the processing unit may be a rolling mill, a break-down unit, a chemical treatment unit, a coating unit, an annealing unit or the like.
Horizontal strip storage units and vertical strip storage units are known in the art. The strip travels through these storage units while forming loops. The individual loops or loop strands are guided over stationary and movable deflection rollers. The movable deflection rollers are arranged on roller tables in the case of vertical storage units and in looping carriages in the case of horizontal storage units. The roller cables or looping carriages are connected to a tension drive which serves to generate the necessary strip tension or the desired tension in the loop strands of the strip.
When the strip travels around the deflection rollers, bending and friction losses occur, particularly when metal strip having a thickness of 1.5 mm to 6 mm is being processed. These bending losses add up from loop strand to loop strand. For structural reasons, the diameter of the deflection rollers is not large enough to permit an elastic travel of the strip around the rollers. For example, in the case of a steel strip having a yield point of 250 N/mm.sup.2 and a thickness of 2 mm, a roller diameter of 1680 mm is required. In the case of a strip thickness of 6 mm, the roller diameter must even be 5000 mm. However, for cost reasons and for reasons of space availability, the rollers which are usually used have a diameter of only between 1000 mm and 1500 mm. In rollers having these diameters, extremely high bending and friction losses occur in the range of the above-mentioned strip thicknesses. These losses are unacceptable for technical and economical reasons. Moreover, higher processing speeds and greater strip storage capacities and coils are required to an increasing extent, so that the strip treatment plant or its processing unit can be operated continuously with high strip speed.